The Royal Navy was so gripped by a security panic over gay servicemen in the late 1960s, admirals believed at least half of the entire fleet had "sinned homosexually".

Documents released by the Public Record office reveal commanders buried a series of scandals including homosexual affairs on an aircraft carrier, transsexual prostitutes in the Far East and hundreds of men using a "male brothel" in Bermuda.

One admiral concluded that homosexual activity was "rife" and a special inquiry called for more moral education to prevent the defences being undermined.

The ban on homosexuals serving in the armed forces was only lifted in January 2000 after a protracted human rights battle.

Permissive society

Sir Winston Churchill once reportedly said that the only naval traditions were "rum, sodomy and the lash".

There is, regrettably, ample evidence that homosexual practices are rife in the Fleet ... I have a strong [belief] that many of the men are not perverts

Admiral Sir John Fitzroy Duyland Bush

But the navy had long insisted that gay personnel were not only detrimental to good discipline but also prey to blackmail.

Servicemen were either disciplined or discharged for homosexuality under military law.

But by the late 1960s social attitudes were changing as the government legalised homosexuality.

The age of permissiveness, however, had failed to permeate the navy as commanders uncovered a string of scandals in 1968.

By the end of that year 40 men had already been discharged for homosexual relationships, many of them linked to events on the aircraft carrier HMS Eagle.

Discharges: Rose amid Bermuda and Eagle crises

While the details of that event are not recorded, the admirals believed that the larger "Bermuda case" exposed more than 400 men to potential blackmail by foreign agents.

The documents reveal a local man on the island ran a brothel frequented by sailors.

There, they took part in "grossly indecent acts and [posed] for sexually perverted photographs".

Special investigators found the Bermudan man kept the names of the men and their ships, both in a special address book and on the back of the photographs.

The urgent report concluded that all the 400 men needed to be specially interviewed because they were "blackmailable" by foreign powers.

Whether or not they were discharged is not reported.

Singapore prostitute crisis

The high command in London brought in retired captain Donald MacIntyre to investigate.

Twiss: "Time for less permissive attitude"

His findings included a potential health disaster in Singapore where sailors who had caught diseases from local male or transsexual prostitutes, known as Catamites, were afraid to reveal the source of their infections.

One sailor reportedly picked up a prostitute who he believed to be female. Realising he wasn't who she appeared to be, the sailor reportedly declared: "Blimey, you're all there!" Nevertheless, he apparently became "infatuated".

This kind of incident led admirals to argue that most of the men accused were only inadvertently homosexual, rather than dangerous "perverts".

Back in London, Admiral Sir John Fitzroy Duyland Bush, head of the Western Fleet wrote to all commanders.

"There is, regrettably, ample evidence that homosexual practices are rife in the Fleet," he told captains.

"I have a strong [belief] that many of the men are not perverts but basically normal men whose standards of behaviour are thoroughly lax."

Admiral Sir Frank Roddam Twiss, the Second Sea Lord, became involved, warning commanders to be on the look out for "unnatural vice" attributable to changing moral attitudes in civil life.

"The time has come to take a less permissive attitude in the Fleet," he said.

Divisions at the top

But not all of the top brass agreed.

The then head of naval law, considering the staffing implications of mass dismissals, appeared to encourage the navy to accept the permissive society.

There have been military forces who have accepted homosexuality but who nonetheless been renowned both for bravery and discipline

Chief lawyer's memo

He urged admirals to recognise the "current astonishingly rapid changes in sexual morality of the whole western world".

The Navy, he warned, would lose promising men because of youthful indiscretions which were not necessarily a threat to national security.

Commanders worried at the possibility of losing men had confided to him that "50% of the fleet have sinned homosexually at some time in their naval career".

If that were the case, he went on, then the navy was only afloat because it was not very efficient at rooting out the offenders.

While the policy of discharging offenders involved in public acts of indecency in front of "hand-clapping audiences" was valid, there should be more flexibility in the rules, he argued.

"There have been military forces who have accepted homosexuality but who nonetheless have been renowned both for bravery and discipline," he wrote.

"It is not necessary to carry out a witch hunt for the more discreet offenders ... that it goes on discreetly and hidden away need not cause us too much dismay."

This recommendations appeared to be rejected. By the middle of 1969, a new education programme was in place.

All new recruits would be lectured on the evils of homosexuality - and commanders were instructed to watch out for further crises that could play into the hands of a blackmailing enemy.